Here's some choices from http://www.allelectronics.com/" onclick="window.open(this.href);return false; but they are all the same price and style. They also state that the key is removed in the "on" position, and I don't know if that means circuit open or closed when "on".The key circuit must be "closed" when "on" to trigger the relay.

Do you need a relay? Depends on the key switch/remote switch that you use. You need a rating of AT LEAST 30 amps for most Power Wheel type applications. Finding a key switch that will handle more then 15 amps is challenging, and the 15 amps ones are really expensive. Also, many remotes come with relays, but typically it isn't large enough to handle 30 amps.

For a key switch, you'll most likely cut one of the wires coming off the battery, and put the relay in that line.

For a remote kill switch, doing the above is an option, but I think a better setup is if the remote not only cuts the power, but also applies the stock brakes, to possibly save kids in a panic situation. Here's a diagram to show how to do that:

A couple notes about the diagram above:

- The above diagram was specifically for a new style, Power Wheels brand wiring harness, with a single battery and an all-in-one high/low/reverse shifter. Different models will look different. The important thing is to cut the power to the motors, and to get the braking effect it must be redirected from the motors through the braking circuit.

- The colors vary from model to model. The diagram above should show an "orange" wire as the brake wire, not cyan, as that is the most common. But it's NOT the only color ever used.

- The resistor isn't always present. Seems the newest models of Power Wheels don't use them at all. Adding one is an option, and is covered in other topics. Even if you don't have a resistor, you would still connect to the braking circuit!

- I don't show a diode between the remote and the relay. I probably should. When the relay drops, it sends a huge power burst back that could cook the remote, depending on how well it handles current. Anything rated for 6 amps or more (all the ones in the links above) probably won't have a problem. The diode would go between the positive and negative wires between the remote and the relay. It won't flow any current normally, but it shorts out that spike coming back.

As an option, you could tap an indicator light off of the positive wire between the remote and the 30 amp automotive relay. Ground it to the same place you are grounding the remote. This way when the remote is enabled you will know it by seeing the indicator light.

This could be important because even though the remote relay only draws power while actively switching, the 30 amp automotive relay coil will be draining power the entire time the vehicle is enabled. You would want to make sure that the remote is off when you put it away so that the battery doesn't go dead in the vehicle when not using it.

You could go one step further and use a lighted switch instead of an indicator light. Not only would it give you the lighted warning, but you can use the switch to manually cut power to the automotive relay if the keychain remote is not with you at the time. The positive wire from the remote would go to the main power contact on the lighted switch. Connect the ground wire from the lighted switch to the same place you are grounding the remote. And instead of having the trigger wire from the automotive relay going directly to the remote, have it go to the NO (normally open) contact on the lighted switch. Note that this would only be a manually override for turning the system off. You would have to have both the switch on and the remote in the on position to drive the vehicle. But if only the switch or only the remote is off, the vehicle would be off.

Due to popular demand, here's a variation of the diagram to use a remote on an 18 volt (or 24 volt) system:

There are a lot of combinations of modifications... I'm not about to draw a diagram for every one, but I can give some quick hints.

If you want to run a key switch AND a remote shut-off, simply put the key switch in the circuit that supplies power TO the remote. This way it still only requires a single relay. In my diagrams, it's the wire furthest to the right. By having it there, power will be cut to the remote, which will then cause the relay to drop into it's "OFF" state. This will also keep the remote from draining the battery... a nice addition.

Adding a NOS setup with a remote or key switch? I haven't put any thought into a NOS setup..... but for starers, look at the "higher voltage" diagram. Put in a SPDT switch (likely a relay) that switches the power wire going INTO the throttle switch to change between being connected to just the 12 volt battery in one position, or the 2 batt's in series in the other position.